Study on magnetic field distribution and electro-magnetic deformation in wire electrical discharge machining sharp corner workpiece

Sharp corner is a common characteristic in many precise parts, and wire electrical discharge machining (WEDM) is a popular method for manufacturing sharp corner parts because the corner radius processed by WEDM is much less than that by traditional tool cutting. But, the experiment results show that there is an inevitable corner deformation caused by electro-magnetic force in WEDM when workpiece thickness is less than 5 mm. This paper aims to analyze and decrease this inevitable corner deformation. Firstly, a set of corner cutting experiment is implemented to obtain the characteristic of corner deformation, and it can be found that the corner deforming direction of Al alloy is opposite to that of Q235 steel. Additionally, a finite element model (FEM) is established to analyze the magnetic field distribution and qualitatively reveal the formation mechanism of electro-magnetic deformation in single pulse discharge machining. Then, two empirical formulas between corner deformation and input factors are acquired by the method of generalized regression fitting. Eventually, two practical methods are proposed to improve corner accuracy, including adjusting machining parameters and adapting the programmed wire path. Moreover, confirmative experiment data shows that the corner deformations of 6061 Al alloy (Q235 steel) is reduced from 213 μm (97 μm) to 21.6 μm (55.9 μm), respectively.